Strategies for increasing accrual in cancer clinical trials: What is the evidence?

Abstract Introduction Despite the importance of clinical trial participation among cancer patients, few participate—and even fewer patients from ethnic and racial minoritized groups. It is unclear whether suggested approaches to increase accrual are successful. We conducted a scoping review to identify evidence‐based approaches to increase participation in cancer treatment clinical trials that demonstrated clear increases in accrual. Notably, more stringent than other published reviews, only those studies with comparison data to measure a difference in accrual rates were included. Methods We searched PubMed/MEDLINE, Embase, CINAHL, and Web of Science for English‐language articles published from January 1, 2012, to August 8, 2022. Studies were included if they were conducted in the United States, described single or multicomponent interventions, and provided data to measure accrual relative to baseline levels or that compared accrual rates with other interventions. Results Sixteen articles were included: six with interventions addressing patient barriers, two addressing provider barriers, seven describing institutional change, and one describing policy change. Key themes emerged, such as a focus on patient education, cultural competency, and building the capacity of clinics. Few studies provide comparative accrual data, making it difficult to identify with certainty any effective, evidence‐based approaches for increasing accrual. Some patient‐ and system‐level interventions studies showed modest increases in accrual primarily through pre‐post measurement. Conclusion Despite an extensive body of literature about the barriers that impede cancer treatment trial accrual, along with numerous recommendations for how to overcome these barriers, results reveal surprisingly little evidence published in the last 10 years on interventions that increase accrual relative to baseline levels or compared with other interventions. As clinical trials are a primary vehicle through which we improve cancer care, it is critical that evidence‐based approaches are used to inform all efforts to increase accrual. Strategies for increasing participation in cancer clinical trials must be developed and rigorously evaluated so that these strategies can be disseminated, participation in trials can increase and become more equitable, and trial results can become more generalizable.


| INTRODUCTION
Receiving cancer treatment within a clinical trial is considered high-quality care, 1,2 but access to and participation in these trials is low and inequitable.Data show that longer survival and lower mortality are correlated with clinical trial participation. 3 However, less than 8% of people with cancer participate in a cancer treatment clinical trial. 4Moreover, it is estimated that only about 15% of those participating are from racial and ethnic minoritized groups 4,5 even though these groups comprise more than 40% of the US population.This underrepresentation is particularly concerning given the higher incidence of cancers, and known inequities in outcomes, among Black/African American and Hispanic/Latino populations in particular. 6For decades, data have consistently shown that groups underrepresented in cancer treatment trials include people from ethnic and racial minoritized groups, [7][8][9] people with low incomes, 9,10 those who live in rural areas, 11 people who are aged 70 years and older, [12][13][14] and adolescents and young adults aged 15-39 years. 15t is critical to improve equity in access to cancer treatment clinical trials and in particular, address barriers faced by racial and ethnic minoritized groups and other underrepresented populations; these barriers occur at the levels of the patient, clinician/research team, institution, and system. 16,17 or example, often-cited barriers facing patients generally include awareness, attitudes, and concerns about travel and cost. 5Further upstream barriers facing clinicians include failure to prescreen patients for eligibility, biases about discussing trials as an option for treatment 18 and assumptions about a patient's treatment preferences. 19At the health systems level, cancer treating facilities may face limited availability of clinical trials, restrictive eligibility criteria in available trials, 20 limited staffing and infrastructure capacity and capability, [21][22][23] ineffective patient screening and enrollment practices, 16,[24][25][26][27][28][29][30][31] or poor community engagement. 5,30 ross all potential barriers, however, there has been very little documentation of evidence showing what works to increase accrual.We sought to identify any available evidence about approaches or interventions for increasing cancer treatment trial accrual rates, overall or for any particular population group, focusing only on studies that provided evidence that could be used to assess whether an approach improved accrual, and if so, by how much.Additionally, we sought to determine whether there was evidence to indicate that the effectiveness of interventions to increase accrual in cancer treatment clinical trials differed by any subgroup, such as by race/ethnicity, geographical location, or cancer type.
This scoping review differs from other recent reviews of approaches to increase US cancer treatment trial accrual in important ways.Other reviews, concluding that certain approaches have improved accrual, utilized different definitions of accrual 32 /participation, or different inclusion criteria (e.g., including treatment, screening and cancer control studies). 33,34 ifferent from many other reviews, this scoping review requires that studies present comparison data to measure a difference between intervention groups or change over time from baseline in accrual rates in the same population.We believe these data are critical to establish the effectiveness of any intervention.

| METHODS
We conducted a scoping literature review by searching PubMed/MEDLINE, Embase, CINAHL, and Web of Science for English-language articles published from January 1, 2012, to August 8, 2022, from the United States.The complete search strategy for all data sources is provided in Appendix.The search strategy included a number of cancer-related terms and required that studies focused on accrual of participants into cancer treatment trials.
Three researchers completed title and abstract review for inclusion, with the inclusion or exclusion determined by consensus when there was initial disagreement.Two researchers then completed the full article review for inclusion, where disagreements were resolved via consensus.
Studies were included if they were conducted in the United States, described single or multicomponent approaches are used to inform all efforts to increase accrual.Strategies for increasing participation in cancer clinical trials must be developed and rigorously evaluated so that these strategies can be disseminated, participation in trials can increase and become more equitable, and trial results can become more generalizable.

K E Y W O R D S
accrual, clinical trials interventions, and provided data to measure accrual relative to baseline levels and/or data that compared accrual rates with other interventions.The outcome of focus was changes in rate of accrual, defined as the number or proportion of cancer patients that enroll in a trial over a specific time frame.Studies that focused primarily on pediatric patients were excluded; trials that focused on adolescents, young adults or adults were included.
One researcher abstracted all of the full articles included.Information about study population, sample size, intervention type, outcomes of interest, methods, and study results was abstracted from all full articles included.Guided by existing literature, 4,35,36 articles were also categorized into four study types: articles describing institutional change, studies addressing patient barriers, articles addressing provider barriers, and articles describing policy changes at the state level.
Only four studies were randomized controlled trials (RCTs); all other studies were pre-post analyses with significant design weaknesses.

| Article characteristics
We identified 2043 nonduplicate records through our initial search.Most (n = 1847) were excluded at the title and abstract phase.Of the 196 articles screened at the full-text phase, the most common reason for exclusion was that the paper did not describe or evaluate a specific intervention.The second most common reason for exclusion was that the study was conducted in a population that did not meet our inclusion criteria (e.g., not in the United States).Furthermore, many studies did not provide any comparative data (including pre-post) that would allow us to quantify a change in accrual.Figure 1 provides a summary of all articles included in the scoping review.
We identified 16 papers that met our inclusion and exclusion criteria.We classified them as six studies addressing patient barriers, one article addressing provider barriers, eight articles describing systems-level change (primarily at the clinic or hospital level), one article focused on clinicians and research staff, and one article describing policy changes at the state level.Several key themes emerged among these interventions, such as a focus on patient education, a focus on cultural competency, and a focus on building the capacity of clinics to improve trial accrual.
Most studies (12 of 16) did not specify cancer types.Still, two focused on breast cancer, one on prostate cancer, one on gynecologic cancers generally, and one on cancer in adolescents and young adults (no specific type).

SYSTEMS -LEVEL CHANGES
Eight articles described institutional changes made to improve clinical trial enrollment (Table 1).These changes included active prescreening and trial matching, multicomponent programming, collaborative clinical programs, and molecular tumor boards.

| Active prescreening and trial matching
Two studies examined implementation of screening strategies to better identify potentially eligible patients through prescreening and trial matching practices, with some reported success.
Rimel et al. 37 compared a web-based online registry and trial matching program to a traditional paper-based registry for gynecological cancer studies.Introduction of the web-based registry was associated with a substantial increase in the number of women participating in the registry, from 5.4 women per month to 23 women per month.Patients who enrolled in the registry through the webbased system were more likely to be non-White than those who enrolled through the paper-based system (25% vs. 15%, respectively; P < 0.001).Of the women who enrolled in the web-based registry, 82% were matched with at least one study, and 15% of those women enrolled but no patients were eligible in the first year for an intervention study.Although the intervention was associated with substantially increased participation in the web-based registry, the paper did not provide data to establish that increased participation in the registry was associated with increased trial accrual.
A quality improvement initiative at a public hospital conducted manual screening by one full-time employee to identify eligible cancer patients through tumor boards, cancer registries, and clinic schedules. 38In the 24 months prior to the program, 31 patients were enrolled in clinical trials.In the 24 months during the study period, 255 patients were identified as potentially eligible for trial enrollment, of whom 143 were successfully initially enrolled (though 15% of those enrolled patients were ultimately found ineligible after enrollment).No data were provided regarding why patients were determined to be ineligible after trial enrollment.The increase in enrollment was 4.6 times over baseline.

| Patient trial matching via molecular tumor boards
We included two studies that examined the use of molecular tumor boards; these studies may provide some indication of the potential for another form of patient matching when made available.Farhangfar et al. 39 compared clinical trial enrollment of patients who underwent molecular profiling alone with those who completed both molecular profiling and the addition of a molecular tumor board through a clinical genomics program at a multisite cancer center with locations across North and South Carolina.Among a cohort of 191 patients reviewed by the tumor board during the first 2 years of the program, 43% who both underwent molecular profiling and review by the tumor board were consented to a clinical trial, and 28% enrolled, compared with only 15% of patients who received only molecular profiling.
Mobley 40 examined the impact of multidisciplinary tumor board (MTB) meetings on consent rate for cancer treatment trials.Patients included in the study were new oncology patients at the University of Iowa Health Care oncology clinics.Of the 11,794 patients included in the study period (2011-2015), 2225 (18.9%) were discussed at MTB meetings.Of these, 92 (4.1%) consented to a clinical trial.Patients whose cases were discussed at MTB meetings gave consent to participate in clinical trials at a higher rate than those whose cases were not discussed (4.1% vs. 2.8%, respectively).However, 76 of the total consented patients in both groups (n = 357 across groups, with 92 in the MTB group and 265 in the non-MTB group) did not enroll in a trial for a variety of reasons, including change in diagnosis or disease stage between time of consenting and start of the study, patient preference, and other reasons.This study may be confounded by the fact that physicians chose which patients should be discussed at tumor board meetings and did not provide data on clinical differences between patient groups.

| Multicomponent programming
Three multicomponent studies used pre-post designs with mixed results.In a multicomponent, community-oriented program 41 at an academic cancer center in an urban, lowincome setting, a team implemented community outreach through physicians and health workers, ensured representation by researchers on the cancer center's executive council, provided grand rounds to raise awareness among investigators, and provided didactic lectures for community providers.There was a significant increase in the proportion of cancer patients enrolled in clinical trials who T A B L E 1 (Continued)  were Black or Hispanic between 2016 and 2018 (12.7% vs. 16.4%;p = 0.0325), despite no significant differences in the rate of clinical trial invitation by race/ethnicity.Anwuri et al. 35 reported on an organizational change model to increase accountability among researchers to improve the accrual of patients of color to therapeutic cancer trials.The framework focused on refining the organizational culture and establishing an infrastructure that reinforced these changes, including a policy of disease-specific accrual targets by race and gender.Clinicians were given benchmarks, and their accrual rates were tracked and documented for monitoring and feedback.Accrual of racial and ethnic minoritized groups was also monitored throughout trial implementation, and a process for communicating feedback to investigators about accrual was formalized.Between 2005 and 2010, there was a small but nonsignificant increase in the proportion of patients of color enrolled in clinical trials, from 12% to 14%, while patients of color represented about 17.5% of the total cancer patient population in treatment at the center during this time frame.
Finally, a clinical trial initiative was implemented at a prostate cancer clinic 42 to inform eligible patients of clinical trial opportunities and provide more detailed treatment recommendations.A practice nurse helped facilitate a discussion about receiving treatment in a clinical trial at specialist visits and provided patients with a summary of their recommendations, including clinical trial options.Between 2004 and 2008, 1370 men with localized prostate cancer were seen at the cancer clinic, 24% of whom were seen before the initiative began.Enrollment in treatment trials increased from 6% to 15%; enrollment in procedural trials decreased from 8% to 2%.

| Collaborative approaches
In an attempt to increase adolescent and young adult (ages 15-40 years) access to clinical trials, a children's hospital and adult cancer program in an urban area developed a collaborative program. 43Adult and pediatric clinicians provided consultation on patients, multidisciplinary meetings were held quarterly where pediatric and adult teams shared information about available trials, and the teams had a shared institutional review board.Clinical trial enrollment from 2006 to 2010 through the initiative was compared with historical enrollment data from the partner institutions from 2003 to 2006.Among adolescent and young adult patients in the program who were treated at the adult hospital, trial enrollment increased from 4% to 32% (p < 0.001).No increase was seen among those treated at the children's hospital.

| INTERVENTIONS TARGETING PATIENT BARRIERS
We identified six studies that focused on interventions intended to reduce barriers at the patient level (Table 2), four of which were RCTs and two were retrospective prepost analyses.Only one of these studies specified the type of cancer (breast). 44Studies either focused on implementing educational tools at the patient level, generally using multiple media, or on the role of lay health workers in educating patients.Although the two pre-post studies reported significant increases in accrual, the RCT data did not demonstrate improvements.

| Multimedia educational tools
Three RCTs and one pre-post study used multimedia education to provide information to patients intended to increase participation in cancer clinical trials.None of the RCTs demonstrated increases in accrual; only the pre-post study reported a significant increase of 7.5%.
Kamen et al. 45 compared a multimedia psychoeducational intervention with a traditional print (control) intervention in 418 patients from National Cancer Institute (NCI) Community Oncology Research.Patients in the intervention group were given the intervention DVD to review, while the patients in the control group were given the standard print materials.At 2 months the proportion of patients in each arm who had opted to enroll in a clinical trial was 117/170 (69%) in the multimedia arm versus 119/192 (62%) in the print arm.A chi-square analysis comparing those who enrolled with either those who declined or who were undecided suggested that there was a significant difference between the groups; however, when the comparison was between enrollees and a combined group of those who were undecided or who declined, there was no significant difference.
The second RCT compared patients at a comprehensive cancer center who viewed a clinical trial educational video in the office with patients who took the same video home. 46The video provided information on clinical trials, including benefits and risks, as well as personal stories from patients and oncologists.One year later, a very small number of participants overall were enrolled in a cancer clinical trial (3/37 in the video intervention group and 2/42 in the usual care group) (p = 0.69).
The third RCT piloted an education video to evaluate a language-concordant multimedia educational tool among 37 Filipino cancer patients in Hawai'i. 47The DVD intervention addressed knowledge about clinical trials, including safety, benefits, and the consent process.The video was presented in two languages (Tagalog and Ilokano) with English subtitles and found no difference in enrollment in the two groups.When patients did decline participation in a trial after the educational video, it was most often because there was a language barrier in the enrollment process itself.
In addition to the RCTs described above, Robinson 44 describes a pre-post evaluation of a 15-minute video intervention with the primary outcome being signing informed consent documents or enrolment in a therapeutic trial within 6 months of intervention.The video addressed six key attitudes toward clinical trials identified among breast cancer patients who are Black.Two hundred female patients who are Black were shown the video.After the intervention, 39 (19.5%) patients consented to or enrolled in a therapeutic trial within 6 months, and 27 (13.5%)were enrolled in a study compared with 6% at baseline (p < 0.001).

| Telephone outreach
Based on the potential for financial reimbursement to support clinical trial accrual, an RCT of telephone outreach compared with the usual pamphlet about available financial reimbursement was conducted in a population of patients who all had financial support available to them. 16oth groups received a pamphlet, but one group received an additional call about the program.There were no differences in clinical trial enrollment (70% in both arms).

| Lay health workers
Finally, Patel et al. 48describe the impact of an intervention using lay health workers directly engaging with racial and ethnic minority union member patients from low-income households who were diagnosed with cancer (nonspecified).Lay health workers assisted patients after their diagnosis and through the process of discussing the care and symptom burden with cancer teams, including educating them about clinical trial participation.The study compared a sample of 66 patients newly diagnosed with cancer with a historical cohort of 72 patients in the 6 months prior to the intervention.Most participants were Black or African American (45% in the intervention group; 46% in the control group) or Asian Pacific Islander (24% in the intervention group; 25% in the control group).More patients after implementation of the intervention enrolled in clinical trials (72%) compared with patients in the 6 months prior to the intervention (22%) (p < 0.001).

CLINICIANS AND RESEARCH STAFF
Only one study described an intervention specifically targeting clinician-level barriers (Table 3), using a cultural competency training for clinical research staff and physician investigators.This pilot study of a 4-h in-person or virtual cultural competency training found no impact on accrual of racial and ethnic minority patients into clinical trials. 49Although the study was directed at both physicians and research staff, only 3% of the volunteers who participated were physicians; the rest were research staff.Accrual in clinical trials was compared at the clinic level between clinics where any individual had participated in training and those that had no volunteer participants.No differences were observed either pre-post at individual centers or between centers.

| POLICY INTERVENTIONS
We identified one policy analysis that met our criteria for inclusion (Table 4).Ellis et al. 50studied the effect of state mandates requiring insurance companies to cover clinical trial costs on patient enrollment in 37 states over 17 years from 1991 and 2007.The analysis compared clinical trial participation through 85 of NCI's Community Clinical Oncology Programs in states with and without mandates.Of 37 states, 13 contributed data both before and after implementation.There was no observed effect of policy mandates, including in multiple sensitivity analyses designed to account for other potential differences, although accrual did increase across all sites, suggesting that other factors were associated with these increases.

| DISCUSSION
This scoping review aimed to identify evidence of strategies that increase accrual, defined as the number of cancer patients enrolled in therapeutic cancer clinical trials or the proportion of eligible patients enrolled in trials.We required that studies specify the time frame over which accrual was measured.This review stands in contrast to prior reviews that do not hold an increase in accrual as the standard for success, specifically accrual relative to baseline levels or compared with other interventions.
Based on the results of this review, it is difficult to identify with certainty any evidence-based approaches that effectively increase accrual in cancer clinical trials, overall or for any particular population group.[53][54][55] Many studies captured in our initial search were eliminated at the abstract phase because their outcome was not accrual into cancer treatment trials or did not provide data that could be used to verify whether an intervention had an effect.No studies were available to determine whether any interventions were more or less effective among patients clinical underrepresented in cancer treatment trials, including people from ethnic and racial minoritized groups, people with low incomes, those who live in rural areas, people who are aged 70 years and older, and adolescents and young adults.
The few studies that do report positive outcomes suffer from a lack of rigorous methods, most notably a lack of comparative methods appropriate for measuring effectiveness, as well as no attempt to enroll a representative sample or to include all eligible patients.Most also provided little detail about the resources necessary to implement the intervention.Many are not specific about the patient population and fail to provide even baseline numbers for the denominator.Strength of study design was inconsistent, and RCTs were only available in patient-level interventions.Most studies included in this review were small, and results for a given intervention were rarely replicated, limiting the strength of evidence for any one intervention and making it impossible to draw firm conclusions about any one intervention being effective or ineffective.
Despite a lack of methodological rigor across most of the studies, those studies that reported positive outcomes generally were those at a system level and included actively prescreening patients and matching them to clinical trials.Having nurses provide tailored summaries of information on clinical trial availability and eligibility to both patients and providers was reported to be associated with increased trial accrual in a pre-post study. 37,42,43 Tough presentation at a tumor board was associated with increased likelihood of enrollment in a therapeutic trial, the decision to present at a tumor board is inevitably at the clinician's discretion, so those cases are more likely to be considered for a trial from the outset and any reported benefit is confounded.
Patient trial matching, based on active prescreening at the system level has also been reported to increase accrual. 38,42 owever, lack of methodological rigor, including a lack of comparative methods, makes it impossible to determine the degree to which such interventions were effective.Approaches that include matching patients to trials require investments in staff resources, both in terms of dedicated staff and time, as well as methods to communicate, and it also is important that reporting on future research in this space better describe the level of resources necessary to achieve success.
The use of lay health workers to assist patients after their diagnosis and through the process of discussing care and symptom burden with cancer teams also was reported to be associated with increases in clinical trial accrual. 48lthough the study was small (n = 66), the benefits of providing a community health worker were realized not only in increasing accrual but also in documentation of goals of care and participation in palliative care.Other systematic reviews have documented the effectiveness of patient navigator interventions at improving clinical trial accrual, especially among patients from ethnic and racial minoritized groups, 56,57 but studies in these reviews were not published within our review time frame.
Although barriers to clinical trial enrollment among cancer patients are multilevel and systemic, a number of approaches to increasing accrual in clinical trials over the past 10 years have continued to focus on changing patient behavior, primarily through education of the individual patient. 58Interventions that focused on patient education made up a large proportion of studies in this review (31%); most studies compare modes of delivery of the same information 45,46 or tailor patient education to specific cultures and languages, 44,47,59 and were predominantly ineffective.
As Unger and colleagues have suggested, the ongoing focus on interventions to address patient barriers suggests that patients themselves are the primary factor limiting trial enrollment and may well be a missed opportunity.Their systematic review and meta-analysis found that system-, institutional-, and clinician-level factors may have a much greater influence on patient

Patient population Comparison/intervention Results
Ellis et al. 50olicy study

Community-based practices in the NCI Community Clinical Oncology Program
State-mandated insurance coverage for trialrelated costs

No effect
Abbreviation: NCI, National Cancer Institute.
participation. 4 They conclude that the root causes of low participation in cancer treatment trials are due to structural and clinical barriers rather those associated with patient willingness or attitudes.Because many of these barriers are potentially modifiable, mitigating those barriers represents an "enormous opportunity to increase trial participation rates."Few studies focused exclusively on provider-and policylevel interventions, although some multicomponent interventions included provider elements.The studies included in this review that did focus on provider-and policy-level interventions found limited or no impact on accrual, had significant limitations, or were outdated.Though Wells et al. 49 focused on improving cultural competency among clinicians, only 3% of those trained were physicians.The one policy study, by Ellis et al., 50 that our review identified found no effect in community oncology programs over several decades of state-level mandates for insurers to provide support for routine costs of care on a clinical trials and is likely not applicable in the current policy environment (e.g., the Affordable Care Act and Clinical Treatment Act) as it was limited to 1991 to 2007.Though Borno et al. 59 included a financial reimbursement component, the financial reimbursement program was available to all patients in the study, so the role of the program itself was not evaluable.Additionally, other factors that affect access to trials such as proximity to facilities conducting clinical trials, equitable offers of clinical trial participation, access to transportation, as well as social determinants of health were not addressed in the studies included in this review.
If we are to improve accrual in cancer treatment trials, we must have evidence-based approaches to inform our recruitment and retention efforts.It is critical that research on interventions that aim to increase accrual employ rigor in study design.Future studies should use directly comparative designs, and RCTs where possible.Studies should ensure that interventions are fully described and that quantitative data are available to make clear inferences about the effect of the intervention in terms of numbers and proportions of participants accrued.Finally, studies should address more clearly any potential confounding.

| Limitations
There were several limitations to our scoping review, both in terms of the design of the review and in the studies available.In limiting our review to studies published in the past 10 years that provided comparative data, either pre-and post-a clearly described intervention, or compared with another intervention, we did not include studies that compared cancer treatment trial accrual rates to national statistics, expected accrual rates or rates from other studies.Our requirement that studies must have included comparison data to demonstrate a difference in accrual rates was notably more stringent than other reviews, but necessary to establish the effectiveness of any interventions.Therefore, some potentially beneficial interventions may have been excluded.Our exclusion of studies published prior to 2012 may have excluded earlier studies that have demonstrated benefit, such as clinical trial navigator programs.Our decision to focus on studies conducted in the United States may have excluded successful approaches used in other countries; however, given the siloed nature of cancer care, the lack of universal health care make the US unique.Moreover, the United States is one of the most racially and ethnically diverse countries in the world; the intersection of different layers of disadvantage and how they impact clinical participation may also be unique to the United States.Finally, our review's reliance on the studies' use of the term "accrual" as defined by the NCI 60 may have affected our conclusions, as it is not defined consistently across investigators, specifically, whether the investigators considered screen failures, participant enrollment, participant randomization, retention, or completion in their use of the term.

| CONCLUSIONS
Clinical trials are vital for advancing cancer discoveries and are considered high quality cancer care, yet very few participate.Moreover, those that do take part are much less diverse than the population of people with cancer. 61If we are to improve the quality of cancer care, it is imperative that we increase overall participation in cancer treatment trials and develop and utilize evidence-based approaches to inform our recruitment and retention efforts.
Despite the robust literature on the barriers to cancer treatment trial participation, often accompanied by promising recommendations or studies suggesting particular strategies, there is a lack of methodologically rigorous research that demonstrates which interventions increase accrual.This same conclusion was reached more than 10 years ago by the National Cancer Institute and the American Society of Clinical Oncology. 53We also note similar conclusions in other systematic reviews of clinical research [62][63][64] in other diseases.
In addition, results of specific tested interventions were never replicated, limiting the strength of evidence for any one intervention and making it impossible to draw firm conclusions regarding efficacy.Finally, no studies assessed the degree to which interventions were effective in increasing accrual among underrepresented groups of patients as compared to other groups.
In conclusion, there is a paucity of high-quality evidence to guide efforts to increase participation in cancer treatment clinical trials.More evidence must be generated to identify which interventions can be effective and for which populations of patients, and what resources are required to replicate them.Moreover, terminology must be standardized in this field of study (e.g., accrual, randomized, enrolled, participation, and completion).It is imperative that strategies for increasing participation in cancer clinical trials be developed and rigorously evaluated so that these strategies can be disseminated, participation in trials can increase and become more equitable, and trial results can become more generalizable.By utilizing evidence-based strategies, we can enhance the speed with which clinical researchers can determine results and bring new treatments to patients who need them.

T A B L E 4
Study of policy-level change.

Study/Type/N Patient population/Setting Comparison/intervention Results
Identification of articles.
Studies targeting patient barriers.
T A B L E 2Abbreviations: FRP, Financial Reimbursement Program; NCI, National Cancer Institute; QI, quality improvement.
Interventions targeting clinicians and research staff.
T A B L E 3Abbreviations: NCI, National Cancer Institute; RTOG, Radiation Therapy Oncology Group.
Search Conducted August 5, 2022.Topic: A scoping review on what approaches have been effective in increasing accrual into clinical trials for cancer.There are systematic reviews about barriers, but few on the effectiveness of interventions/approaches for addressing those barriers.